While authentication systems employing fixed passwords have conventionally been utilized in bank automated teller machine (ATM) systems, online banking systems, and various other types of authentication systems, to further improve security, authentication systems employing disposable one-time passwords have come to be used.
In an authentication system employing one-time passwords, each time that a prescribed period of time has elapsed, the password is changed and a password generation terminal (token) indicating same is distributed to the user, authentication being carried out as a result of manual input into the ATM by the user of the one-time password displayed at this terminal.
However, with conventional authentication systems, it being necessary that the one-time password which is input into the ATM or other such authentication terminal be input thereinto manually by the user, there has been occurrence of problems in that operations for input thereof are annoying, and in that erroneous input can result in unsuccessful authentication.
In light of such problems, one possible solution is to carry out input of a one-time password from a password generation terminal to an authentication device in audio fashion from a speaker of the password generation terminal to a microphone of the authentication device. By so doing, because there is no need to manually input the one-time password, this makes it possible to prevent the annoyance, input errors, and so forth that are associated with manual input.
In accordance with another possible solution, a one-time password might be converted into notes of a musical scale based on a prescribed conversion table, permitting authentication to be carried out based on differences between notes of musical scales. However, because musical scales permit expression of only a small amount of data and because it takes time to transmit notes of a musical scale, this might only allow passwords of small data size to be sent, which might result in lowered security.
Furthermore, at installation locations for authentication terminals and the like there are many noises such as sounds from the surrounding environment which can for example make it difficult to properly recognize musical scale notes at the receiver, this problem being aggravated by the fact that where only a small of data can be transmitted it may be difficult to carry out error correction, as a result of which there may be a high likelihood of occurrence of authentication errors and so forth.
The present invention was conceived in light of such problems, it being an object thereof to provide an authentication system which will make it possible to carry out authentication at high speed and with high accuracy in the context of an authentication system that uses sound to transmit one-time password(s).